C2 : Climatic Test■Perform heat impact test to raise the temperature from -25℃ modified to 2 times of rating current.■No appearance damage such as tracking found in insulation test performed at 80% (40kV) of standard test value (50kV.)

E2 : Environment Test■No abnormality found in the insulation test leaving it in a chamber with 93% of relative humidity for 6 hours or longer.■In addition, no appearance damage found such as tracking in moist penetration test for 144 hours